1. Field of the Invention
The present invention relates generally to optical disk cartridges and apparatus cooperable therewith, and particularly to an arrangement for sealing such a cartridge closed against entry of foreign elements, both during storage and handling of the cartridge and during use thereof in cooperating apparatus.
2. Description of the Prior Art
U.S. Pat. Nos. 4,320,425 and 4,405,136 each disclose a disk cartridge having resiliently flexible top and bottom walls, the bottom wall including a central opening bounded by a circular lip that resiliently presses against a mating annular surface of the hub of a disk inside the cartridge, the top wall including an inwardly extending flange that resiliently holds the hub in sealing contact with the bottom wall lip and the recording portion of the disk spaced from the walls. Operative engagement of the cartridge and hub by cooperating disk-drive apparatus causes both walls to flex out of contact with the hub and thus free the disk for rotation in the cartridge. Such engagement includes supporting engagement of the cartridge bottom wall by a stationary part of the apparatus and driving engagement of the disk hub by a rotatable drive spindle. In U.S. Pat. No. 4,405,136, the stationary part of the apparatus supports the cartridge bottom wall through a pneumatic, pressurized, annular seal that allows only filtered air from within the apparatus to enter the cartridge.
U.S. Pat. Nos. 3, 609,722, 3,529,301, and 4,394,700 each disclose a disk cartridge having top and bottom walls that need not flex in order to be sealed to and unsealed from a disk inside the cartridge. In U.S. Pat. No. 3,609,722, the top and bottom walls each have a central opening bounded by a separate, resilient, compressible, annular washer disposed between the wall and the disk. Each wall is thus sealed to and spaced from the disk by the washer therebetween. Operative engagement of the cartridge and washers by cooperating disk-drive apparatus causes the cartridge bottom wall to be supported by a stationary part of the apparatus and both washers to be compressed by opposing flanges on a rotatable drive spindle. Such engagement not only unseals and frees the disk from each cartridge wall; it also seals and couples the disk to the drive spindle. In U.S. Pat. No. 3,529,301, the top and bottom walls each have a central opening bounded by an annular flange formed by the wall itself so as to mate with a facing surface on the disk hub. Each wall is thus sealed to and spaced from the disk by the flange thereon. The disk is restrained from moving relative to the walls by a spring-loaded brake that normally bears against the disk periphery. Operative engagement of the cartridge and disk hub by cooperating disk-drive apparatus causes the brake to be withdrawn from the disk and the hub to be pushed upwardly away from each wall flange by a rotatable drive spindle. Such engagement frees the disk contact with the cartridge walls and sealingly couples the disk to the spindle. In U.S. Pat. No. 4,394,700, the cartridge bottom wall has a central opening bounded by an annular flange which mates with a corresponding flange on the disk hub. Mounted on or near the wall flange is a plurality of spring-loaded clamping members which normally press the wall flange and hub flange together so as to seal the hub securely to the bottom wall. Operative engagement of the cartridge and hub by cooperating disk-drive apparatus actuates the clamping members, against their spring-loading, to unclamp the flanges and thus free the disk for rotation, while a rotatable spindle in the apparatus drivingly engages the hub.
Prior-art schemes such as those described above may have been satisfactory in some applications, but there remains a need for an improved arrangement by which an optical disk permanently contained in a cartridge is protected against damage or impairment from other objects or contaminants during storage, handling, and use of the disk. Such an arrangement should both restrain the disk from moving inside the cartridge and seal the cartridge closed whenever the cartridge is not operatively positioned for its intended use in cooperating write/read apparatus, but should readily accommodate a disk-drive member of such apparatus and free the disk for rotation thereby whenever the cartridge is so positioned. Such an arrangement should also provide ready optical access to the information-storage medium of the disk by an optical write/read head in the apparatus when the cartridge is operatively positioned therein. Preferably these things should be accomplished by an arrangement that is more efficient, reliable, and durable over the expected life of the cartridge, and simpler and less costly to manufacture, than those employed heretofore.